Water armed air safetied detonator

ABSTRACT

A water-armed, air-safetied fuze for hand grenades, bombs, mines, and torpedoes which permits initiation of the main charge only when the device is underwater. A floodable chamber, having flooding holes to the environment is intermediate an initiator charge, including a delay charge and a transfer charge, and a percussion primer. When water fills the floodable chamber, sufficient forces will be transmitted from the transfer charge to an intermediate firing pin or directly to a percussion primer to initiate the main charge in the ordnance. When air fills the chamber insufficient forces will be transmitted and the device will be safetied.

United States Patent [191 Baker et al.

[ Oct. 16, 1973 WATER-ARMED, AIR-SAFETIED DETONATOR [73] Assignee: The United States of America as represented by the Secretary of the Navy, Washington, DC.

[22] Filed: Mar. 27, 1972 [21] Appl. No.: 238,600

[52] US. Cl. 102/16, 102/64 [51] int. Cl. F42c 15/10 [58] Field of Search 102/10, 16, 19.2,

3,618,522 11/1971 Henderson 102/16 2,928,345 3/1960 Kennedy 102/16 2,601,245 6/1952 Bowersett 102/7 2,660,952 12/1953 Mohaupt 102/16 Primary ExaminerSamuel W. Engle Attorney-R. S. Sciascia et al.

[57] ABSTRACT A water-armed, air-safetied fuze for hand grenades, bombs, mines, and torpedoes which permits initiation of the main charge only when the device is underwater. A floodable chamber, having flooding holes to the environment is intermediate an initiator charge, including a delay charge and a transfer charge, and a percussion primer. When water fills the floodable chamber, sufficient forces will be transmitted from the transfer charge to an intermediate firing pin or directly to a percussion primer to initiate the main charge in the ordnance. When air fills the chamber insufficient forces will be transmitted and the device will be safetied.

4 Claims, 3 Drawing Figures BACKGROUND OF THE INVENTION This invention relates generally to ordnance arm-safe devices and more particularly to a water-armed, airsafetied detonator fuze for grenades or the like. A safety problem exists in the use of hand grenades when they are intended to be thrown from boats into the water because they may be accidently dropped into the boat after the safety cotter pin has been pulled. Accidents have occurred, particularly during night operations when it is more likely to drop a hand grenade in the boat and not be able to retrieve it in time to toss it overboard.

The presently used hand grenades are detonated by first pulling out a cotter pin which retains the hand-held release mechanism for handling and shipping safety. When the grenade is thrown, the hand-held release mechanism separates, from the grenade permitting a spring-loaded firing pin to strike a percussion primer which initiates a pyrotechnic delay fuze coupled to the main charge. The time delay to the detonation of the burster charge is sufficient to provide adequate separation between the thrower and the detonation. But the conventional hand grenade has been found unsafe for use from boats in water operations. An adapter to preclude operation of the grenade except when immersed in water is therefore desired.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an ordnance useful in water.

Another object of the instant invention is to provide an ordnance armed in water and safe in air.

A further object of the present invention is to provide a fuze train having a hiatus when in air and a water piston coupling when submerged in water.

A still further object of the instant invention is to provide a fuze that discriminates between a water and an air environment.

Briefly, these and other objects of the present invention are attained by the use of a floodable chamber interposed in the fuze train between the delay train portion and a percussion primer of a hand grenade. When the chamber is flooded, the water transmits the shock wave energy developed by a transfer charge at the end of the delay train to a percussion primer directly, or to a firing pin that is driven against a percussion primer. Essentially the water in the flooded chamber acts like a water piston transmitting sufficient shock wave energy to fire a percussion primer. When air fills the chamber, because of its compressibility and less density, it will not transmit sufficient shock wave energy to fire the percussion primer. One embodiment of the invention uses a baffle across the floodable chamber to further discriminate between air and water operation by disbursing the shock wave energy produced by the transfer charge.

BRIEF DESCRIPTION OF THE DRAWINGS A more complete understanding of the invention and many of the attendant advantages thereto will be readily understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein:

FIG. 1 is a side view partially cut away of a water armed grenade having a firing pin;

FIG. 2 is a side view partially cut away of a water armed grenade having no firing pin; and

FIG. 3 is a side view partially cut away of a water armed grenade having a baffle between the fuze and percussion primer.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings, wherein like reference numerals designate corresponding parts in the several views, there is shown in FIG. 1, FIG. 2, and FIG. 3 a hand grenade 10 attached to a fuze 12 by a waterarming adaptor 14 according to the invention. When conventionally used on land the hand grenade fuze 12 is threaded directly into the grenade 10.

The hand grenade fuze 12 comprises a conventional hand held release mechanism and retaining cotter pin (both not shown) which when released, ignite a delay charge 16 contained within a bore of a stepped diameter cylinder 18 of the fuze 12 threadably engaged within the adaptor 14. Over the distal end of cylinder 18 is a cup 20 crimped sealed to the cylinder and containing a transfer initiator charge 22 separated from the delay charge 16 by a bore 24 and a washer or disc 26.

Forward of the end of cup 20 is a short passage 28 connected to a floodable chamber 30, having a plurality of flooding holes 32 communicating the flooding chamber to the outside environment.

Coaxial with the passage 28 and communicating with the floodable chamber 30 is a bell-mouthed hole 34. Within the hole 34 sealingly engaged is a firing pin 36 having a blunt-nose and a flared bottom. An O-ring 38 in an annular groove precludes the ingress of waterv Coaxial with the firing pin 36 and separated by a standoff distance'is a percussion primer 40. Separated from the percussion primer 40 by a conduit 42 is a burster charge 44. The conduit 42, in a cylindrical extension 46 of the water-arm adaptor 14, extends within grenade l0 and carries the burster charge 44 which is contained in a cup 48 crimp-sealed to the extension.

Referring now to FIG. 2, another embodiment of the invention is shown wherein the firing pin 36 is eliminated. The configuration is changed to relocate the percussion primer 40 closer to the floodable chamber 30, reducing the diameter of the bell-mouthed hole 34 to that of the conduit 42, and eliminating the O-ring seal 38 in the annular groove.

Referring now to FIG. 3, still another embodiment of the invention is shown wherein the firing pin 36 is eliminated and further differentiation between air-safe and water-arm modes is obtained. In the floodable chamber 30 and across the axis of the passage 28 and the axis of the bell-mouthed hole 34 or the conduit 30 is a cylindrical deflector pin 50 acting as a baffle to the shock wave energy developed by the transfer charge 22.

In operation the sequence of events is as follows in all three embodiments previously described. The release mechanism (not shown) of the conventional hand grenade fuze 12 is hand held as a cotter pin and ring are pulled. When the release mechanism is released, as by throwing the grenade, a spring loaded firing pin (not shown) strikes a percussion primer (not shown, but similar to percussion primer 40) which initiates burning of the delay charge 16. Delay charge 16 eventually burns toward the end adjacent the bore 24 when it produces flashes down the bore 24 to detonate the transfer charge 22. Detonation of transfer charge 22 produces shock wave energy directed into short passage 28 and thence into the floodable chamber 30.

In the FIG. 1 configuration, and when the device is immersed in water, sufficient forces are transmitted through the water causing the flared end of the firing pin 36 to collapse and eject the firing pin into percussion primer 40 detonating it. The flash of the percussion primer 40 detonation initiates the burster charge 44 within the grenade 10.

In the FIG. 2 and FIG. 3 configuration, and when the device is immersed in water the shock wave forces from the transfer charge 22 are transmitted through the water directly to the percussion primer 40 to denote it.

When the floodable chamber 30 does not contain water as when the grenade is thrown to a land target or is dropped in a boat, the delay charge 16 and the transfer charge 22 will be initiated, but the other events to subsequently explode the grenade will be stopped at the floodable chamber 30. The compressibility of air in the chamber and particularly the deflector pin 50 of the FIG. 3 configuration, will disburse the shock wave forces and preclude the detonation of the percussion primer 40. Thus the device renders the hand grenade safe in air and armed in water.

Obviously, numerous modifications and variations of the instant invention are possible in the light of the above teachings. It is therefore to be understood that, within the scope of the appended claims, the invention may be practiced otherwise than as specifically described.

What is claimed as new and desired to be secured by letters Patent of the United States Patent Office is:

l. A water-armed, air-safetied fuze for ordnance comprising:

a hand grenade fuze release mechanism;

a delay charge in said fuze mechanism and initiated thereby;

a transfer charge in said fuze mechanism adjacent and detonated by said delay charge;

an adapter having a substantially cylindrical body and a coaxial bore therethrough, adapted to be threadably engaged between said hand grenade fuze release mechanism at one end and a grenade at the other end;

a floodable chamber constituting an intermediate protion of said bore having radial flooding holes communicating with the environment;

a percussion primer in said bore adjacent said floodable chamber at said other end of said adapter;

a transverse deflector disposed in said floodable chamber across said coaxial bore between said transfer charge and said percussion primer for disbursing an air shock wave away from said primer but not disturbing the shock wave forces transmitted by water flooding said floodable chamber; and

a burster charge adjacent said percussion primer at said other end of said adapter.

2. The fuze of claim 1 further comprising:

a firing pin interposed between said floodable chamber and said percussion primer for striking said percussion primer when sufficient shock wave forces are transmitted .by water filling said floodable chamber.

3. The fuze of claim 2 wherein said firing pin is further defined as having:

a flared skirt in sealing relationship with a hole communicating with said percussion primer; and

a blunt nose for striking said percussion primer.

4. The fuze of claim 1 wherein said deflector comprises: a cylindrical pin. 

1. A water-armed, air-safetied fuze for ordnance comprising: a hand grenade fuze release mechanism; a delay charge in said fuze mechanism and initiated thereby; a transfer charge in said fuze mechanism adjacent and detonated by said delay charge; an adapter having a substantially cylindrical body and a coaxial bore therethrough, adapted to be threadably engaged between said hand grenade fuze release mechanism at one end and a grenade at the other end; a floodable chamber constituting an intermediate portion of said bore having radial flooding holes communicating with the environment; a percussion primer in said bore adjacent said floodable chamber at said other end of said adapter; a transverse deflector disposed in said floodable chamber across said coaxial bore between said transfer charge and said percussion primer for disbursing an air shock wave away from said primer but not disturbing the shock wave forces transmitted by water flooding said floodable chamber; and a burster charge adjacent said percussion primer at said other end of said adapter.
 2. The fuze of claim 1 further comprising: a firing pin interposed between said floodable chamber and said percussion primer for striking said percussion primer when sufficient shock wave forces are transmitted by water filling said floodable chamber.
 3. The fuze of claim 2 wherein said firing pin is further defined as having: a flared skirt in sealing relationship with a hole communicating with said percussion primer; and a blunt nose for striking said percussion primer.
 4. The fuze of claim 1 wherein said deflector comprises: a cylindrical pin. 